This invention relates to apparatus and system for terminating the winding wires of a dynamoelectric machine and more specifically to such apparatus and system which enables the winding wires to be terminated in a terminal block and which permits the ready installation of other electrical components, such as a thermal protector or a starting switch for the motor.
Generally, a dynamoelectric machine, such as a fractional horsepower motor, includes a stator assembly comprised of a stack of platelike laminations punched from suitable sheet ferro-magnetic material. As is conventional, each of the laminations has a central opening therein and a plurality of blind notches or slots extending generally radially outwardly from the central opening so as to form a plurality of slots surrounding the central opening. Depending on the type and winding scheme for the motor, a plurality of coils of copper wire, referred to as magnet wire, are inserted in respective slots of the stator core so as to form the windings for the motor. For example, the windings for a typical fractional horsepower motor may include a main winding and an auxiliary winding. The magnet wire constituting the main and auxiliary windings of the motor have ends which must be connected to lead wires for properly energizing the windings of the motor so as to permit startup and operation of the motor.
Heretofore, it was conventional that the ends of the magnet wire constituting a winding of the motor would be physically connected, as by soldering or the like, to a flexible leadwire which in turn could be selectively connected to a source of electrical power. The requirement of making these junctions between the lead wire and the magnet wire was time consuming and relatively expensive. Further, these lead wire/magnet wire junctions were a potential source of failure for the motor during its service life. In an effort to eliminate the requirement of magnet wire-to-lead wire junctions, several techniques have been proposed.
In U.S. Pat. No. 3,725,707 to Leimbach et al, a pair of electrically insulative terminal blocks is affixed to the end face of the stator core of a motor and a tubular terminal is inserted into openings provided in the terminal blocks. The ends of the windings are placed in channel portions of the terminals which are then crimped over on the winding or magnet wires. Then, a lead wire with a bayonet-type terminal thereon may be inserted into the tubular portion of the terminal thereby to make electrical connection between the winding or coil wire and the leadwires. However, the system and terminals disclosed in the above-mentioned patent required that the terminals be crimped on the coil wires and this presented difficulties in automating the process.
In U.S. Pat. Nos. 3,979,615, 3,984,908 and 4,041,604, another system for electrically connecting the ends of the winding coils to the lead wires is disclosed in which the coil wires are inserted in respective slots of an electrically insulated terminal block bonded to the end face of the stator core with the coil wires extending across a receptacle. Then, a slotted terminal is forceably inserted into the receptacle whereby a slot in the terminal receives the magnet wire extending across the receptacle, and strips the electrical insulation from the outer surfaces of the magnet wire thereby to make electrical contact between the magnet wire and the terminal. Simultaneously with inserting the terminal into the receptacle of the insulative terminal block, the excess length of the magnet wire was cut off by a blade so as to present a neat installation of the magnet wire in the terminal block. The terminal has barbs or tabs thereon which positively prevent its removal from the receptacle within the terminal block. Then, a respective lead wire with a terminal thereon may be readily connected to the terminal received in the receptacle so as to electrically connect the lead wire to its respective magnet wire.
While the systems of U.S. Pat. Nos. 3,979,615, 3,984,908 and 4,041,604 overcame certain of the problems exemplified in U.S. Pat. No. 3,725,707 (i.e., eliminating the requirement of having to crimp the magnet wires to the terminals), the insulative blocks shown in U.S. Pat Nos. 3,984,908 and 4,041,604 were relatively large injection molded plastic parts which, of necessity, had to be secured to the entire end face of one end of the stator core. Thus, these mounting blocks were relatively expensive and covered a considerable portion of the end face on the stator core. Additionally, separate fastening means were required so as to positively secure these terminal blocks to the end faces of the cores.
U.S. Pat. Nos. 4,071,793 and 4,177,397 disclose smaller terminal blocks which are securable onto the end faces of the stator core for receiving magnet wires from the windings of the motor for connection to lead wire terminals.
U.S. Pat. No. 4,251,911 discloses a method of terminating the coil windings of an electric motor in which, after the coil winding wires have been inserted in their slots so as to extend transversely across a respective terminal receptacle, the winding wire is successively wrapped around a so-called binding post. Then, upon insertion of the terminals into the receptacles, a blade movable with the terminals engages both the magnet wire wrapped around the binding post and severs both the wire and the binding post from the terminal block. However, this method requires that the winding wire be wrapped around the binding post.
U.S. Pat. No. 4,322,647 discloses still another type of terminal block which is secured to one end face of the coil.
Still another problem present in the manufacture of dynamoelectric machines, and particularly in the manufacture of fractional horsepower motors, is the problem of connecting a so-called thermal protector to the windings. Typically, a thermal protector carries the current to the main windings of the motor and is sensitive to the operating temperature of the motor and to the amount of current flowing through the windings so that in the event the current flowing through the windings becomes excessive (such as in the event of a locked rotor or the like), the thermal protector will open the circuit to the main windings thus interrupting the flow of current. Oftentimes, after the windings and the thermal protector have cooled below a predetermined temperature level, the thermal protector will reset thus allowing the electric motor to restart.
While certain thermal protectors are miniaturized devices which mav be incorporated in the windings of the motor, it is more typical, especially on larger size fractional horsepower motors (e.g., one quarter horsepower and above) which are conventionally used in many home appliances such as in clothes dryers, washing machine motors, dishwashers and the like, that the thermal protector be of relatively large size and have relatively large terminals so as to readily accommodate the flow of current through the motor windings. While these thermal protectors may vary considerably in size depending on the model, the manufacturer, and the load rating of the protectors, a typical size of the protector may, for example, be about 1.38 inches (3.5 cm.) long by 1 inch (2.54 cm.) wide and about 1/4 inch (0.64 cm.) thick. Oftentimes these thermal protectors are mounted on the starting switch, the end shields or other convenient structure of the electric motor.
Various arrangements for mounting the motor's starting switch for proper operation of the starting switch by a centrifugal actuator have been proposed. For example, in the coassigned U.S. Pat. No. 3,782,669, a bracket is provided on which the starting switch is mounted and this bracket serves to mount the thermal protector in close proximity to the starting switch so that electrical connections between the thermal protector and the starting switch may be readily made.
U.S. Pat. No. 4,163,913 discloses a motor protector mount which is installed in the motor and which is specifically designed to mount the thermal protector in a desired location within the motor.
U.S. Pat. No. 4,250,419 discloses a holder for an overload protector which includes a so-called thermal protector pocket member of formed sheet metal construction which is slipped into place between the end turn bundles of the windings. Then the thermal protector is inserted into a pocket formed in the pocket member and various lead wires are connected to the thermal protector so that electrical power flowing to the windings may flow through the protector.
However, all of these various schemes for mounting relatively large physical size thermal protectors in a motor fail to take advantage of the various schemes for permitting automatic termination of the magnet wires forming the windings of the motor and oftentimes require additional jumper leads and the like and additional terminals on the motor starting switch. These additional leads can, of course, be accidentally misconnected, or the terminals on the leads or the starting switch may be damaged during handling or shipping of the motor so that it is not possible to make a proper connection or such that a failure would be likely to occur during operation of the motor.
Further, in the assembly of motors of different horsepower ratings, the magnet wire for the windings varies widely in diameter. It is essential that once the magnet wire is inserted across the receptacles of the terminal block, but before the terminal has been inserted into the receptacle that the magnet wire be firmly held centered within the receptacle. Heretofore, this has required the provision of terminal blocks with slots of different widths to receive the different magnet wire diameters. This has resulted in added expense by necessitating the manufacture and stocking of a large number of different terminal blocks to accommodate the different wire sizes.
Among the several objects and features of this invention may be noted the provision of an apparatus and system for terminating the winding wires of a dynamoelectric machine, such as a fractional horsepower motor or the like, which eliminates lead wire assemblies and connections thus reducing costs and improving the quality and reliability of the motor;
The provision of such apparatus and system which eliminates the requirement for a separate mounting clip or bracket for the thermal protector for the motor again reducing the cost and complexity of the motor;
The provision of such apparatus and system which permits a thermal protector to be inserted directly into a terminal connected to the magnet wire ends from the windings of the motor thus eliminating the number of connectors required so as to connect the windings to the thermal protector and to the motor starting switch;
The provision of such apparatus and system which eliminates or reduces the possibility of misconnecting various lead wires to the terminals of the thermal protector and to the motor starting switch;
The provision of such apparatus and system which lends itself to manufacturing operations in which the terminals connecting the magnet wires to the terminals may be automatically inserted into the receptacles of their respective terminal blocks;
The provision of such an apparatus and system in which the terminal blocks may be readily mounted on the core of the stator assembly and in which the terminal block does not interfere with the insertion of the windings into the slots of the stator core and in which the terminal block does not interfere with subsequent forming and blocking operations of the end turns of the windings;
The provision of such an apparatus and system in which the magnet wires from the windings are securely held in place extending across their respective receptacles of the terminal block until such time as the terminal is forceably inserted thereinto so as to prevent the magnet wires from becoming displaced from their respective terminals, regardless of the diameter of the magnet wire;
The provision of such an apparatus and system in which a relatively few terminal blocks accommodate a wide variety of magnet wire diameters; and
The provision of such apparatus and system which facilitates production, which lowers the cost of manufacturing the motor, and which leads to greater reliability and a longer service life for the motor.
Other objects and features will be in part apparent and in part pointed out hereinafter.